VEGETABLES. 98 



of the palm tree is called in commerce Sago; that 

 from the roots of the Maranta arundinacea of the West 

 Indies is known as Arrow-root ; and that from the root 

 of the manioc tree is the well-known tapioca of the 

 shops. All these — starch, sago, arrow-root, and tapi- 

 oca — are substantially the same thing. They are all 

 washed with cold water from the substances in which 

 they are respectively found. 



 



166. Starch, gum, and sugar contain no nitrogen 

 They are all characterized by the letters CHO, signi- 

 fying carbon, hydrogen, and oxygen. 



167. On the other hand, gluten, caseine, and albu- 

 men are nitrogenous substances. All of them contain 

 nitrogen, and all contain sulphur and a very little 

 phosphorus. Their principal ingredients being car- 

 bon, hydrogen, oxygen, and nitrogen, they are char- 

 acterized by the letters CHON, expressive of their 

 composition. 



168. One or more of these nitrogenous substances 

 exist in all plants. 



169. Gluten is a very important constituent of 

 wheat. It is insoluble in water. Hence, if you chew 

 a kernel of wheat, the gluten will remain in the 

 mouth after the rest will have disappeared ; or, if you 

 wash wheat flour over a cloth, the gluten will remain 

 on the cloth, a tough, stringy, grayish substance, 

 while the starch and the albumen will pass through. 



